• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 추계종합학술대회논문집
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• pp.121-124
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• 2000

We propose an algorithm for almost unsupervised detection of linear structures, in particular, axes in road network and river, as seen in synthetics aperture radar (SAR) images. The first is local step and used to extract linear features from the speckle radar image, which are treated as road segment candidates. We present two local line detectors as well as a method for fusing Information from these detectors. The second is hybrid step, we Identify the real roads among the segment candidates by defining a Markov random field (MRF) on a set of segments, which introduces contextual knowledge about the shape of road objects.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.221-224
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• 2000

We propose an algorithm for almost unsupervised detection of linear structures, in particular, axes in road network and river, as seen in synthetics aperture radar (SAR) images. The first is local step and used to extract linear features from the speckle radar image, which are treated as road segment candidates. We present two local line detectors as well as a method for fusing information from these detectors. The second is global step, we identify the real roads among the segment candidates by defining a Markov random field (MRF) on a set of segments, which introduces contextual knowledge about the shape of road objects.

• 한국통신학회논문지
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• 제35권9C호
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• pp.771-777
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• 2010

본 논문은 공간다중화 multiple input multiple output (MIMO) 시스템을 위한 새로운 신호검출 기법인 QR-OSIC with Candidates (QOC) 기법을 제안한다. 제안하는 QOC 기법은 부분적인 successive interference cancellation (SIC) 알고리즘과 maximum likelihood (ML) metric 연산을 이용하여 많은 수의 후보 심볼 벡터 없이 최적 성능과 유사한 성능을 얻는다. 제안된 QOC 기법은 hard, soft decoding 시스템에서 모두 동일한 알고리즘으로 변경없이 사용할 수 있다. 특히, soft decoding 시스템을 위한 송신 신호의 모든 비트의 log likelihood ratio (LLR)을 기존 LLR estimation 알고리즘 없이 효율적으로 생성 가능하다. 제안된 신호검출 기법은 고정된 연산복잡도를 가지며 파이프라인 구조로도 구현이 가능하므로 VLSI 구현에 효율적인 특성을 보인다. $4{\times}4$ 16-QAM MIMO 시스템을 위한 신호검출 기법을 VLSI 구현을 통하여 비교한 결과 QOC 신호검출기가 K-Best 신호검출기에 비해 27% 크기를 가지면서 하드웨어 지연은 더욱 작은 것을 확인 할 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.27-30
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• 2004

OFDMA is considered as one of the major candidates for broadband wireless access. The OFDMA signal is usually coherently demodulated, requiring the channel estimation which can be estimated using a known pilot signal. In multi-cell environment, the performance of channel estimation is mainly limited by intercell interference. It is desirable to use a pilot signal that can estimate the channel information robust to the intercell interference in the OFDMA uplink system. In this paper, we consider two types of pilot signal applicable to multi-cell OFDMA uplink systems: One is time-multiplexed pilot signal and the other is code­multiplexed pilot signal. Simulation results show that the code-multiplexed pilot is suitable for low mobility environment and time-multiplexed pilot is suitable for high mobility environment.

• 반도체디스플레이기술학회지
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• 제10권3호
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• pp.53-59
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• 2011

This paper proposes a new method of traffic signal detection and recognition in an RGB color model. The proposed method firstly processes RGB-filtering in order to detect traffic signal candidates. Secondly, it performs adaptive threshold processing and then analyzes connected components of the binary image. The connected component of a traffic signal has to be satisfied with both a bounding box rate and an area rate that are defined in this paper. The traffic signal recognition system is implemented using C language in an embedded Linux system for a high-speed real-time image processing. Experiment results show that the proposed algorithms are quite successful.

• 한국통신학회논문지
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• 제34권6C호
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• pp.642-648
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• 2009

본 논문에서는 LRA (Lattice Reduction-Aided) 검출 기법에서 격자 감소를 위하여 주로 사용되어 오던 LLL(Lenstra-Lenstra-Lovasz)을 대신하여 SA (Seysen Algorithm)를 이용함으로써, 복잡도의 감소와 함께 성능 향상을 이루었다. 이러한 성능향상에도 불구하고 여전히 존재하는 SA-LRA 검출 기법과 ML 검출과의 성능 차이를 줄이기 위하여 list of candidates 기법을 SA-LRA 검출 기법에 적용하였다. List of candidates 기법은 송신 신호 벡터가 될 수 있는 후보들의 리스트를 구성하여, 이 중 최소의 유클리디안 거리 (Euclidean Distance)를 가지는 후보를 송신 신호 벡터로 추정하는 기법이다. 모의실험 결과는 이 기법을 통하여 SA-LRA 검출 기법이 ML 검출과 유사한 성능을 가질 수 있음을 보이고 또한, SA를 통하여 채널 행렬이 보다 더 직교성을 가지게 되는 것을 보인다.

• 한국자동차공학회논문집
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• 제24권2호
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• pp.214-224
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• 2016

This paper proposes an algorithm to effectively detect the traffic lights and recognize the traffic signals using a monocular camera mounted on the front windshield glass of a vehicle in day time. The algorithm consists of three main parts. The first part is to generate the candidates of a traffic light. After conversion of RGB color model into HSI and YCbCr color spaces, the regions considered as a traffic light are detected. For these regions, edge processing is applied to extract the borders of the traffic light. The second part is to divide the candidates into traffic lights and non-traffic lights using Haar-like features and Adaboost algorithm. The third part is to recognize the signals of the traffic light using a template matching. Experimental results show that the proposed algorithm successfully detects the traffic lights and recognizes the traffic signals in real time in a variety of environments.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.1-10
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• 2018

Wide-area monitoring of tree-related high impedance fault (THIF) efficiently contributes to increase reliability of large-scaled network, since the failure to early location of them may results in critical lines tripping and consequently large blackouts. In the first place, this wide-area monitoring of THIF requires managing the placement of sensors across large power grid network according to THIF detection objective. For this purpose, current paper presents a framework in which sensors are distributed according to a predetermined risk map. The proposed risk map determines the possibility of THIF occurrence on every branch in a power network, based on electrical conductivity of trees and their positions to power lines which extracted from spectral data. The obtained possibility value can be considered as a weight coefficient assigned to each branch in sensor placement problem. The next step after sensors deployment is to on-line monitor based on moving data window. In this on-line process, the received data window is evaluated for obtaining a correlation between low frequency and high frequency components of signal. If obtained correlation follows a specified pattern, received signal is considered as a THIF. Thereafter, if several faulted section candidates are found by deployed sensors, the most likely location is chosen from the list of candidates based on predetermined THIF risk map.

• Journal of Positioning, Navigation, and Timing
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• 제7권2호
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• pp.53-59
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• 2018

This paper proposes a pseudo-random beamforming technique for time-synchronized mobile base stations (BSs) for multi-cell downlink networks which have mobility. The base stations equipped with multi-antennas and mobile stations (MSs) are time-synchronized based on global positioning system (GPS) signals and generate a number of transmit beamforming matrix candidates according to the predetermined pseudo-random pattern. In addition, MSs generate receive beamforming vectors that correspond to the beam index number based on the minimum mean square error (MMSE) using transmit beamforming vectors that make up a number of transmit beamforming matrices and wireless channel matrices from BSs estimated via the reference signals (RS). Afterward, values of received signal-to-interference-plus-noise ratio (SINR) with regard to all transmit beamforming vectors are calculated, and the resulting values are then feedbacked to the BS of the same cells along with the beam index number. Each of the BSs calculates each of the sum-rates of the transmit beamforming matrix candidates based on the feedback information and then transmits the calculated results to the BS coordinator. After this, optimum transmit beamforming matrices, which can maximize a sum-rate of the entire cells, are selected at the BS coordinator and informed to the BSs. Finally, data signals are transmitted using them. The simulation results verified that a sum-rate of the entire cells was improved as the number of transmit beamforming matrix candidates increased. It was also found that if the received SINR values and beam index numbers are feedbacked opportunistically from each of the MSs to the BSs, not only nearly the same performance in sum-rate with that of applying existing feedback techniques could be achieved but also an amount of feedback was significantly reduced.

• 융합신호처리학회논문지
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• 제19권4호
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• pp.199-205
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• 2018

기존의 전영역 탐색 방법의 많은 계산량으로 인하여 예측 화질 향상과 연산량 감축을 위한 연구가 진행되어 왔으며, 본 논문에서는 전영역 탐색기반의 방법과 비교하여 예측화질은 거의 유지하면서 효율적으로 계산량을 줄이는 방법을 제안한다. 제안하는 알고리즘은 다중 문턱치 필터를 이용하여 각 후보 지점에 대하여 부분 블록 에러 합을 계산하고, 이를 여러 문턱치 필터에 적용하여 각 후보들을 영역별로 분류 또는 제거하고, 이에 따라 다음 단계에서 진행할 후보들을 선별하고, 최소 에러지점의 최적후보에 대해 단계별 부동 회수를 비교 판단하여 그 다음 단계의 진행 여부를 결정함으로써 최적의 움직임 벡터를 고속으로 계산한다. 이를 통하여 전체의 최소블록매칭에러를 갖는 움직임 벡터를 조기에 발견하고, 불필요한 후보들을 더 빨리 제거함으로써 불필요한 계산량을 줄이고 계산속도 향상을 얻을 수 있다. 또한 제안하는 알고리즘은 단독으로 사용할 뿐만 아니라 기존의 고속 알고리즘들과 결합하여 사용해도 예측화질대비 우수한 연산량 감소를 얻을 수 있으며, 실험결과에서 이를 검증한다.